The Government has yet to make a convincing case as to why the £50 billion HS2 high-speed rail project, which would run between London and Birmingham and the north of England, is necessary, a highly-critical report by a House of Lords committee has said.

There are less-expensive options than HS2 for solving overcrowding on the railways but these have not been properly reviewed, the Lords Economic Affairs Committee said.

HS2 was supposed to rebalance the economy but it is London rather than the Midlands or the North that is likely to be the biggest beneficiary from HS2, the peers said.

The first phase of HS2, from London to Birmingham, is due to open in 2026, with a second Y-shaped phase to Manchester and Leeds due for completion around 2032/33, although this date might be brought forward.

In its report, the committee said there was a strong case for improving the trans-Pennine links (the so-called HS3 option) or building the second phase of HS2 first.

Both of these options would be a better way of rebalancing the economy than constructing the London-Birmingham phase.

The peers also said that cutting the speed of the HS2 trains from 250mph to 200mph would reduce the cost, as would terminating the southern end of the line at Old Oak Common in north west London rather than at Euston.

The peers called on the Government to make a convincing case for the project before Parliament passed the HS2 Bill.

Commenting on the report, the committee’s chairman Lord Hollick said: “At £50 billion HS2 will be one of the most expensive infrastructure projects ever undertaken in the UK but the Government have not yet made a convincing case for why it is necessary.

“The committee are supportive of investment in rail infrastructure, but are not convinced that HS2 as currently proposed is the best way to deliver that investment.”

He went on: “The Government are basing the justification for HS2 on two factors - increased rail capacity and rebalancing the UK economy; we have not seen the evidence that it is the best way to deliver either.

“The plausibility of the Government’s claim that there are current long-distance capacity constraints and also its forecast of future passenger demand are difficult to assess without full access to current railway usage. The investment of £50 billion investment of public money demands nothing less than full transparency.”

Lord Hollick said that, in terms of rebalancing the economy, “London is likely to be the main beneficiary from HS2”.

He added: “Investment in improving rail links in the North of England might deliver much greater economic benefit at a fraction of the cost of HS2.”

A Department for Transport spokesman said: “We have been fulIy transparent about the project. HS2 will deliver over £2 of benefits for every £1 invested and the economic benefit of the project was recognised by MPs of all parties who voted 452 to 41 in favour of HS2 at the second reading of the hybrid Bill.”

He added: “It is crucial we press ahead with delivering HS2 on time and budget and we remain on track to start construction in 2017.”

Stop HS2 campaign manager Joe Rukin, of Kenilworth, said: “We very much welcome the findings of this report, as the Lords have paid attention to what so many of us have been saying for five years about the case for HS2, and have concluded that there isn’t a case for HS2.”

Taxpayers’ Alliance chief executive Jonathan Isaby said: “This damning report takes apart every one of the arguments for HS2 and taxpayers will demand that politicians listen.

“There is no capacity case, no business case and no value-for-money case, and this expensive vanity project will take scarce resources away from where they’re really needed on the rail network. It’s time to scrap this scheme before taxpayers get landed with the bill for a costly white elephant.”

The Rail Delivery Group, which represents Network Rail and train operators, said: “HS2 can transform the rail network and the rail industry is working closely with government, HS2 Ltd, passenger groups and suppliers to maximise the benefits of this important project.”